1. Field of the Invention
The present invention relates to precision measurement apparatuses, and particularly to a measurement apparatus used for a light guide plate.
2. Description of Related Art
With the rapid development of liquid crystal displays (LCDs), the light guide plate, as one of the key components of an LCD, has also undergone great development. For assuring good quality, measurement apparatuses are used in many of the stages of manufacturing of the light guide plate.
A conventional measurement apparatus comprises a setting frame, a light source fixing device, and a base plate for the placement thereon of a light guide plate to be measured. The light source fixing device and the base plate are both disposed on the setting frame opposite to each other. The base plate can move on the setting frame along a single axis, so as to change the horizontal distance between the light source fixing device and the base plate. In use, a light source contained in the light source fixing device emits light to illuminate the light guide plate on the base plate. Optical instruments are disposed at the side of a light emitting surface of the light guide plate to collect the measurement data.
Since the light source fixing device is fixed on the setting frame, the light guide plate and the light source fixing device are in a same plane. Therefore the measurement apparatus cannot imitate the condition of oblique incidence of light; that is, light received from a source which is not in the plane defined by the light guide plate. In addition, the base plate can only be moved along a single axis. Therefore the measurement apparatus cannot imitate the condition of deviation; that is, light received from a source which is in the same plane as that of the light guide plate but which is not aligned therewith. As a result, the measurements are limited in scope, and do not necessarily indicate the performance of the tested light guide plate under various circumstances.
It is desired to provide a measurement apparatus for a light guide plate which overcomes the above-described problems.